The overall mission of the Virology/Immunology Core is to enhance HIV-related research and promote collaborations among HIV investigators, by providing improved access to virologic and immunologic assays, clinical specimens, and recombinant DMA constructs. The specific aims of this Core are: 1. To provide a centralized repository for clinical specimens and HIV-related recombinant DMA constructs that can be used by clinical, behavioral, and laboratory investigators. 2. To centralize, and improve access to, state-of-the-art virologic assays for clinical, behavioral, and laboratory investigators. 3. To provide a centralized facility that produces recombinant proteins relevant to HIV research. 4. To provide expertise in the design and interpretation of flow cytometry assays, and to improve access to the shared instrumentation necessary to conduct these studies. 5. To provide improved access to existing URMC core facilities. This core will utilize and augment already existing infrastructures, such as those in the Cold Storage Facility (Aim 1), Infectious Diseases Unit laboratories (Aim 2), Human Immunology Center (Aim 4), and existing core facilities (Aim 5) at the URMC. In addition, we will centralize expression of certain recombinant proteins (Aim 3), in order to provide economy of scale to investigators that use them in HIVrelated research. The Virology/Immunology Core will implement the overall mission of the UR D-CFAR by supporting a broad base of investigators from the UR and its international collaborators in South Africa, and promoting interdisciplinary collaborations among them.